@sortedarray=
map{ $_->[0] }
  sort{ $a->[1] cmp $b->[1] || 
		$a->[2] <=> $b->[2] || 
		$a->[3] cmp $b->[3] 
	  }
       map { 
	        if ( m/^(.+?)\((\d+)\)\s-\s\[(.+?)\].+?"(.*?)"\.$/ )
              {
               my ($disc_file,$page,$key,$val) = ($1,$2,$3,$4);
			   [$_,$disc_file,$page,$key];
              }
           } <DATA>;

foreach(@sortedarray){
  print "$_\n";
}

__END__
CD1\01100809.pdf(1) - [Account Number] Indexed key "654546654".
CD2\01100809.pdf(1) - [Invoice Date] Indexed key "10/08/2001".
CD1\01100809.pdf(1) - [Customer Name] Indexed key "FOOBAR".
CD2\01100809.pdf(1) - [Contact Name] Indexed key "Dr. FOO".
CD4\01100809.pdf(20) - [Account Number] Indexed key "54356564".
CD4\01100809.pdf(20) - [Invoice Date] Indexed key "10/08/2001".
CD1\01100809.pdf(20) - [Customer Name] Indexed key "FOOBAR".
CD1\01100809.pdf(20) - [Contact Name] Indexed key "Dr. FOO".
CD1\01100814.pdf(33) - [Account Number] Indexed key "56357576537".
CD3\01100814.pdf(33) - [Invoice Date] Indexed key "10/08/2001".
CD3\01100814.pdf(33) - [Customer Name] Indexed key "FOOBAR".
CD1\01100814.pdf(33) - [Contact Name] Indexed key "Dr. FOO".
CD2\01100813.pdf(27) - [Account Number] Indexed key "73677576".
CD3\01100813.pdf(27) - [Invoice Date] Indexed key "10/08/2001".
CD1\01100813.pdf(27) - [Customer Name] Indexed key "FOOBAR".
CD3\01100813.pdf(27) - [Contact Name] Indexed key "Dr. FOO".